There are a few small errors in the lower right hand corner of the picture: S1 (the opening close to the drivers) should be S4, and S4 (the close end of the duct inside the box) should be S1; in general, all the S's refer to the cross-sectional areas of the tube (or duct): S2 is on the side of the drivers (pick the middle between the two drivers) pointing towards the closed internal duct, and S3 is on the side of the drivers (again, in the middle between the drivers) pointing towards the mouth. S1 is the throat (close end in this case), and S4 is the mouth (opening close to the drivers). All the L's (e.g.: L12) refer to the distances between the S's.

I highly recommend you spend some time in Hornresp, there are a number of good tutorials on the web.

Looks like bjorno's design from Post #3 will work well.
I highly recommend you spend some time in Hornresp, there are a number of good tutorials on the web.

Regards,

I have spent the better part of the last month in horn response and have went through numerous tutorials. I think my problem is understanding the different types of horns and converting the numbers to an acutal box.

I can make a simple tapped horn fairly easily in hornresp, but I don't understand the difference between the designs and how hornresp is doing what it does.

If you are not in a hurry we can help you to sort out concept issues...

Submitting a picture revision of what Oliver have noticed here-above:

b

PS: The important distance here is L23 but L12 can be slightly off easily to correct with the necessary needed damping material. This can be shown in simulations, i.e. by using MJK:s or the AKAbak program.

Movies you say, my specialty I like those two drivers in a 4ft^3 ported box tuned to 25Hz with a 3" x 10" slot port 27.6" long. pic below. This design would let you upgrade to a 500w amp and have reference spec.

In one of the guides I was reading, S2 can be as small as 1/4 the Sd of the driver, but many drivers will work better with this dimension being larger. This is the "throat" or compression area so it's fairly important that this not be any larger than the Sd from my understanding (I could be wrong on this so someone feel free to chime in). It's also important not to go smaller than 1/4Sd as I guess that can cause problems.?

The same guide said that a good starting ballpark for S4 is driver Sd x 2 but this may change as you optimize the simulation.

After simming your driver in hornresp awhile, I'm convinced that this horn loading stuff is a lot more hype than anything. The best arrangement I could come up with produced similar efficiency and loading characteristics as the 6th order bandpass box I suggested above, however, the box would be nearly twice the size, and perform ~3db worse in maximum output compared to the 6th order bandpass configuration.